Fix for RG smoothing width?

nifty/spaces/lm_space/lm_space.py

@@ -165,7 +165,9 @@ class LMSpace(Space):
         return res
 
     def get_fft_smoothing_kernel_function(self, sigma):
-        # FIXME why x(x+1) ? add reference to paper!
+        # cf. "All-sky convolution for polarimetry experiments"
+        # by Challinor et al.
+        # http://arxiv.org/abs/astro-ph/0008228
         return lambda x: np.exp(-0.5 * x * (x + 1) * sigma*sigma)
 
     # ---Added properties and methods---

nifty/spaces/rg_space/rg_space.py

@@ -284,7 +284,7 @@ class RGSpace(Space):
         return dists
 
     def get_fft_smoothing_kernel_function(self, sigma):
-        return lambda x: np.exp(-0.5 * np.pi*np.pi * x*x * sigma*sigma)
+        return lambda x: np.exp(-2. * np.pi*np.pi * x*x * sigma*sigma)
 
     # ---Added properties and methods---